Back spot facer



June 3, 1930. A. CHRISTENSEN BACK SPOT FACER Filed June 16, 1927 ATTORNEY Patented June 3, 1930 V UNEE sTA'rEs A ENT oFFIcE anxnnnoi-misrnnsnn, or new YORK, N; Y.

ACK sror PACER Application filedJune 16,1927. Serial No. 199,153.

' Thisinvention relates to cutting tools and more particularly to back spot facing cutters. 1 1 I An object of the invention is to provide a simple and effective tool for spot facing metalin relatively inaccessible positions.

One of the important features of the invention relates to the provision of interchange able parts which may readily be assembled in lo a variety ofc'ombinations so that the work may be done to desired dimensions and may.

be accurately centered with respect to differ ent sizedholes. "In order to employ the tool l in differently sized holes and to work to different dimensions according to the character of the work required, the tool may bereadily and easily dismantled and quickly assembled.

Another feature ofthe invention relates to Accordincrto another feature a lurallkey drive is provided, thus giving increased strength and more accurate alm'ement under workmg pressure. y

0," Accordingtost1ll another feature a retaining ring holdsthe cutting tool in posi-- tion and distributes andequalizes the strains set up during the cutting operation.

Another important feature of the invention is the provision of a back spot facing tool of simple construction which is economical to manufacture and which may be readily formedof conventional raw material .readily available inthe market. v I

'Other'objects will appear'from thefollowing description taken in connection with the accompanying drawings in which Fig. 1 is a vertical cross-section of a dis- 7 metal which is to be operated upon;

Fig. 2is a view of the assembled'toolin operation; V

' Fig.3 is a section taken on theline 33-of so Fig.1;

sible.

bar 20.

Fig. '4 is a vertical cross-section of the cutter and Fig. 5 is a section taken on the line 55 of Fig. 4.

Like reference characters denote like parts in the several figures of the drawing.

In the following description and claims, 1

parts, characteristic features and functions 7 W1ll he identified by specific means for convenience of expression, but they are intended to be as generic in their application to similar parts or equivalent construction as the art will permit. p i I Referring to Fig. 1 there is shown a mass of metallO to be Worked on, having a hub portion 11, which terminates in a flange 12. I Theflange 12 is apertured as at 13 and it is understood. that it is desired to provide a smooth machined surface at 14, which .may

i be intended, for example, to serve as the seat at for a nut. It will 'beseen that in order to spot facethe surface 14 it is necessary to operate through the aperture 13, as the, surface to be operated on is relatively inacces- For this purpose there is provided a bar 7 20, having its drive end 21 splined for engagement with a drivingclutch of convention-a1 form (not shown). The bar. is formed of heat treated alloy steel. The free L end of thebar is accurately turned to a round cross-section as at 22, this section being sufiiciently elongated to permit operatingthrough holes of considerable depth, as may be found necessary. A pilot holder 23, substantially 5 cup shaped in form and having a bore conforming to the section 22 of the bar20 is mounted thereon and isheld securelyin place by 'ablind set screw. 24, the point of which enters a shallow notch 25 in the bar 20. A pilot 26, having a bore also conforming to the i section 22- of the bar 20 andhavingits outer wall conforming to the sides of the aperture 13'111 td tl mantled tool-shown in proximity to a mass of 18 01m 6 on 19 bar 20 so that one end 27 thereof enters the cupped recess of the pilot holder 23. "A blind set screw 28 mounted in the periphery of the pilot holder 23 engages the pilot26 and maintains it infixed position relative to the pilot holder 23 and the ill , shoulder 4.5 of the cutter 40.

dimenslon of the ring 52 1s such 1t seats For separably supporting a cut-ting tool the free end of the bar 20 is provided with a pair of oppositely positioned slots or keyways as at 30, 31. Each of these slots extend longitudinally of the bar 20 for some distance from the end of the bar, and is widened as at 32 so as to communicate with a second but relatively short slot 33 in parallel relation with the slot 30. The slots shown are for a left hand drive tool; for a right hand drive it is necessary to interchange the slots 33 and 30.

A cutter 420 (see Fig. 4) formed of high speed tool steel is apertured as at il to fit snugly on the free end of the bar 20. One end wall 42 is provided with a plurality of cutting teeth 43 for shearing away metal with which the face 12 may be in contact. The cutting edges may be for left hand drive as shown, or reversed for right hand drive as desired. The outer end of the cutter a0 is chamfered as an to form an inclined shoulder 45, thus forming a seat for a retaining ring as will subsequently be set forth. A pair of oppositely disposed slots 46, 47 is cut in the peripheral wall'of the cutter is extending longitudinally of the cutter from its chamfered end.

For maintaining the tool in assembled form there is also required a pair of keys as at 50,

51, and a ring 52. Ring 52 slips over the tool and keys for the purpose of securing the keys to the tool member. Each key has a length conforming to the longitudinal dimension of the widened portion 32 of the slot in the bar 20, and a width such that it extends into the slot as indicated in Figs. 3 and 5. The ring 52 is formed of a metal slightly softer than the metal of the cutting tool and one edge is beveled to conform to the incline of the The internal snugly on the chamfered end of the cutter 40.

The tool'is assembled by selecting a pilot having an outer dimension conforming .to the size of the aperture 13 through which it is intended to operate. The dash dot line (Fig. 1) indicates the outline of a' larger pilot suitable for a larger aperture than that shown. -The pilot isslipped into the pilot holder 23 and fastened by the set screw 28 as has been described. The bar 20 and pilot 26 are now inserted in the aperture 13. The keys 50, 5.1 are now inserted in the slots 46, 47 of a tool 40, the proper size of tool being selected for the work to be done. is then applied to the cutter, and the assembled cutter is mounted on the end of the bar 20, a double bayonet joint being provided by the protruding keys 50, 51 in connection with 3 the slots in the end of the bar.

In operation the bar 20 is rotated, carrying with it the cutting tool 40 which shears off the surface l tof the metal. The operation may be continued as long as desired until a desired machlned surface is obtained.

The ring 52.

It will be seen that in operating the tool a balanced drive is obtained, thus providing more strength and greater accuracy in alinement. Thedriving surface is of considerable length and thus the slots in the bar can be relatively shallow, thereby avoiding undesirable weakening of the bar. The slots and keys can readily be made as long as desired to secure needed strength. The long contact provided effectively avoids any tendency to burr up the parts or of one part attempting to ride over another part of the device. The parts are easily and quickly dismantled by hand without the aid of wrenches. When the pilot becomes worn it can be inexpensively replaced, thus saving the cost ofa complete bar. 7

Where only one side of aperture is to be operated upon continuously a pressed-on fit of the pilot may be employed instead of the interchangeable pilot holder illustrated in the drawings without departing from the spirit of the invention. Other modifications will suggest themselves to those skilled in the art and it is understood that the scope of the invention is not to be determined by the specific form herein disclosed for the purpose of illustration, reference being had to the appendant claims for that purpose.

Vhat is claimed is:

u 1. A back spot facing tool device comprising a bar having a plurality of keyways, means positioned on said bar for accurately centering said bar with respect to work to be cut, a spot facing cutter, and means for securing said cutter on the end ofsaid bar comprising a plurality of keys for engaging said keyways to secure a balanced drive, and a ring positioned over said cutter and said keys for maintaining said keys in position and for distributing torsion strains about said device.

2. A back spot facing device comprising a bar having a plurality of elongated shallow keyways, means positioned on said bar for accurately centering said bar with respect to work to be out, a spot facing cutter, and means for securing said tool on the end of said bar comprising a plurality of relatively long keys for engaging said keyways to secure a balanced drive, and a ring positioned over said cutter and said keys for maintaining said keys in position and for distributing torsion strains about said device.

3. The combination with a holder member having a pilot sleeve detachably mounted thereon, of a tool member detachably mounted upon said holder member and adapted to be driven thereby, said holder member having a plurality of slots cut in the end thereof, a

plurality of keys, for engaging said slots respectively, and means comprising aringpositioned over said toolmember andsald keys for securing said keys to said tool member.

4. The Combination with a holder member having a pilot sleeve, detachabl mounted thereon, of a tool member detacha ly mounted upon said holder member and adapted to be driven thereby, said holder member having a plurality of elongatedslots cut in the end thereof, a plurality of elongated keys for en gaging said slots respectively, and means comprising a ring positioned over said tool member and said keys and for securing said keys to said tool member. s

5. The combination with a holder member having a recessed end to form an inclined shoulder, a pilot sleeve detachably mounted thereon, of a tool member detachably mounted upon said holder member and adapted to be driven thereby, said holder memberhaving a plurality of slots cut in the end thereof, a plurality of keys for engaging said slots respectively, and means comprising an internally bevelled ring positioned over said tool member and said keys and engaging said recessed end for securing said keys to said tool member.

6. The combination With a driving member having a pilot sleeve detachably mounted thereon, of a driven member detachably mounted upon said driving member and adapted to be driven thereby, said driving member having a plurality of slots cut symmetrically in the end thereof, a plurality of keys for engaging said slots respectively, and means comprising a ring positioned over said driven member and said keys for securing said keys to said driven member.

7. The combination With a-holder member 7 having a pilot sleeve detachably mounted thereon, of a cutting tool detachably mounted upon said holder member and adapted to be driven thereby, said holder member having a plurality of slots cut in the end thereof, a plurality of keys for engaging said slots respectively, and means comprising a ring positioned over said cutting tool and said keys for securing said keys to said cutting tool.

8. The combination with a holder member having a pilot sleeve detachably mounted thereon, of a cutting tool detachably mounted upon said holder member and adapted to be driven thereby, said holder member having a plurality of diametrically opposed slots cut in the end thereof, a plurality of keys for engaging said slots respectively, and means comprising a ring positioned over said cutting tool and said keys for securing said keys to said cutting tool.

Signed at Harrison, in the county of Hudson and State of New Jersey, this 15th day of June, A. D. 1927.

ANKER L. CHRISTENSEN. 

